1. Field of the Invention
The present invention relates to a both-side recording apparatus capable of automatic both-side recording on a recording sheet, and particularly to an ink jet recording apparatus for recording with an ink jet process. The present invention relates particularly to an arrangement of a conveying roller and a configuration in a front-back side inversion apparatus.
2. Related Background Art
For automatic both-side recording in an ink jet recording apparatus, several methods have been commercialized or proposed. In these methods, after recording on a front side (top side) of a recording sheet, the conveying direction thereof is reversed to feed the recording sheet into a front-back side inverting apparatus, and, after an inverting operation, the recording sheet is conveyed again by the same sheet conveying unit as in the recording operation on the front side to execute recording on the back side of the recording sheet by the same recording unit.
Among these methods, U.S. Pat. No. 6,332,068 discloses an invention in which the front-back side inverting apparatus is provided with two drive rollers whereby the conveying direction of the recording sheet is inverted by 180° along a conveying path. In the prior apparatus of such configuration, the recording sheet is conveyed with a recorded surface outside in the front-back side inversion apparatus. Also a configuration of inverting the conveying direction of the recording sheet by 180° by a main drive roller and an auxiliary drive roller is known, for example, in Japanese Patent Application Laid-open No. 2002-59598. Also in the apparatus of such configuration, as in the aforementioned example, the recording sheet is conveyed with a recorded surface outside in the front-back side inversion apparatus.
However, these prior examples have been associated with certain limitations.
More specifically, there is considered generation of an axial loss by a certain reason between a supporting axis of an idler roller and the idler roller in the front-back side inversion apparatus, and, in case such torque becomes unnegligible in comparison with the torque of a frictional force which the idler roller receives from the recording sheet, the idler roller may cause a defective rotation. In such case, in the prior technology in which the drive roller is in contact with a non-recorded surface of the recording sheet and the idler roller is in contact with the recorded surface of the recording sheet, a defective rotation of the idler roller may cause a friction or scrape between the idler roller and the recorded surface of the recording sheet thereby causing a detrimental influence on the recorded result such as a partial peeling of a recording material (or recording agent) if the recorded recording material is not completely fixed.
Also as the non-recorded surface of the recording sheet is contacted with an elastic member while the recorded surface of the recording sheet is contacted with a non-elastic member, the surface of the roller contacting the recorded surface is often a smooth surface of a low friction coefficient. For this reason, in case the recording material remains on the roller contacting the recorded surface, for example it is peeled and remains on the idler roller as explained before, it involves a risk of re-deposition in another portion of the recording sheet thereby resulting in a fear of deteriorating the recorded result.
Also in case of conveying with the recorded surface outside as in the prior technology, a roller contacting the recorded surface of the recording sheet has a relatively smaller diameter, whereby a given portion on the circumference of the roller has a higher frequency of contacting the recorded portion, whereby a possibility that the recording material peeled as explained before is accumulated on the roller and is re-deposited onto the recording sheet is elevated.